libstdc++
fstream
1 // File based streams -*- C++ -*-
2 
3 // Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
4 // 2006, 2007, 2008, 2009
5 // Free Software Foundation, Inc.
6 //
7 // This file is part of the GNU ISO C++ Library. This library is free
8 // software; you can redistribute it and/or modify it under the
9 // terms of the GNU General Public License as published by the
10 // Free Software Foundation; either version 3, or (at your option)
11 // any later version.
12 
13 // This library is distributed in the hope that it will be useful,
14 // but WITHOUT ANY WARRANTY; without even the implied warranty of
15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 // GNU General Public License for more details.
17 
18 // Under Section 7 of GPL version 3, you are granted additional
19 // permissions described in the GCC Runtime Library Exception, version
20 // 3.1, as published by the Free Software Foundation.
21 
22 // You should have received a copy of the GNU General Public License and
23 // a copy of the GCC Runtime Library Exception along with this program;
24 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
25 // <http://www.gnu.org/licenses/>.
26 
27 /** @file fstream
28  * This is a Standard C++ Library header.
29  */
30 
31 //
32 // ISO C++ 14882: 27.8 File-based streams
33 //
34 
35 #ifndef _GLIBCXX_FSTREAM
36 #define _GLIBCXX_FSTREAM 1
37 
38 #pragma GCC system_header
39 
40 #include <istream>
41 #include <ostream>
42 #include <bits/codecvt.h>
43 #include <cstdio> // For BUFSIZ
44 #include <bits/basic_file.h> // For __basic_file, __c_lock
45 #ifdef __GXX_EXPERIMENTAL_CXX0X__
46 #include <string> // For std::string overloads.
47 #endif
48 
49 _GLIBCXX_BEGIN_NAMESPACE(std)
50 
51  // [27.8.1.1] template class basic_filebuf
52  /**
53  * @brief The actual work of input and output (for files).
54  * @ingroup io
55  *
56  * This class associates both its input and output sequence with an
57  * external disk file, and maintains a joint file position for both
58  * sequences. Many of its semantics are described in terms of similar
59  * behavior in the Standard C Library's @c FILE streams.
60  */
61  // Requirements on traits_type, specific to this class:
62  // traits_type::pos_type must be fpos<traits_type::state_type>
63  // traits_type::off_type must be streamoff
64  // traits_type::state_type must be Assignable and DefaultConstructible,
65  // and traits_type::state_type() must be the initial state for codecvt.
66  template<typename _CharT, typename _Traits>
67  class basic_filebuf : public basic_streambuf<_CharT, _Traits>
68  {
69  public:
70  // Types:
71  typedef _CharT char_type;
72  typedef _Traits traits_type;
73  typedef typename traits_type::int_type int_type;
74  typedef typename traits_type::pos_type pos_type;
75  typedef typename traits_type::off_type off_type;
76 
77  typedef basic_streambuf<char_type, traits_type> __streambuf_type;
78  typedef basic_filebuf<char_type, traits_type> __filebuf_type;
79  typedef __basic_file<char> __file_type;
80  typedef typename traits_type::state_type __state_type;
81  typedef codecvt<char_type, char, __state_type> __codecvt_type;
82 
83  friend class ios_base; // For sync_with_stdio.
84 
85  protected:
86  // Data Members:
87  // MT lock inherited from libio or other low-level io library.
88  __c_lock _M_lock;
89 
90  // External buffer.
91  __file_type _M_file;
92 
93  /// Place to stash in || out || in | out settings for current filebuf.
94  ios_base::openmode _M_mode;
95 
96  // Beginning state type for codecvt.
97  __state_type _M_state_beg;
98 
99  // During output, the state that corresponds to pptr(),
100  // during input, the state that corresponds to egptr() and
101  // _M_ext_next.
102  __state_type _M_state_cur;
103 
104  // Not used for output. During input, the state that corresponds
105  // to eback() and _M_ext_buf.
106  __state_type _M_state_last;
107 
108  /// Pointer to the beginning of internal buffer.
109  char_type* _M_buf;
110 
111  /**
112  * Actual size of internal buffer. This number is equal to the size
113  * of the put area + 1 position, reserved for the overflow char of
114  * a full area.
115  */
116  size_t _M_buf_size;
117 
118  // Set iff _M_buf is allocated memory from _M_allocate_internal_buffer.
119  bool _M_buf_allocated;
120 
121  /**
122  * _M_reading == false && _M_writing == false for 'uncommitted' mode;
123  * _M_reading == true for 'read' mode;
124  * _M_writing == true for 'write' mode;
125  *
126  * NB: _M_reading == true && _M_writing == true is unused.
127  */
128  bool _M_reading;
129  bool _M_writing;
130 
131  //@{
132  /**
133  * Necessary bits for putback buffer management.
134  *
135  * @note pbacks of over one character are not currently supported.
136  */
137  char_type _M_pback;
138  char_type* _M_pback_cur_save;
139  char_type* _M_pback_end_save;
140  bool _M_pback_init;
141  //@}
142 
143  // Cached codecvt facet.
144  const __codecvt_type* _M_codecvt;
145 
146  /**
147  * Buffer for external characters. Used for input when
148  * codecvt::always_noconv() == false. When valid, this corresponds
149  * to eback().
150  */
151  char* _M_ext_buf;
152 
153  /**
154  * Size of buffer held by _M_ext_buf.
155  */
156  streamsize _M_ext_buf_size;
157 
158  /**
159  * Pointers into the buffer held by _M_ext_buf that delimit a
160  * subsequence of bytes that have been read but not yet converted.
161  * When valid, _M_ext_next corresponds to egptr().
162  */
163  const char* _M_ext_next;
164  char* _M_ext_end;
165 
166  /**
167  * Initializes pback buffers, and moves normal buffers to safety.
168  * Assumptions:
169  * _M_in_cur has already been moved back
170  */
171  void
172  _M_create_pback()
173  {
174  if (!_M_pback_init)
175  {
176  _M_pback_cur_save = this->gptr();
177  _M_pback_end_save = this->egptr();
178  this->setg(&_M_pback, &_M_pback, &_M_pback + 1);
179  _M_pback_init = true;
180  }
181  }
182 
183  /**
184  * Deactivates pback buffer contents, and restores normal buffer.
185  * Assumptions:
186  * The pback buffer has only moved forward.
187  */
188  void
189  _M_destroy_pback() throw()
190  {
191  if (_M_pback_init)
192  {
193  // Length _M_in_cur moved in the pback buffer.
194  _M_pback_cur_save += this->gptr() != this->eback();
195  this->setg(_M_buf, _M_pback_cur_save, _M_pback_end_save);
196  _M_pback_init = false;
197  }
198  }
199 
200  public:
201  // Constructors/destructor:
202  /**
203  * @brief Does not open any files.
204  *
205  * The default constructor initializes the parent class using its
206  * own default ctor.
207  */
208  basic_filebuf();
209 
210  /**
211  * @brief The destructor closes the file first.
212  */
213  virtual
214  ~basic_filebuf()
215  { this->close(); }
216 
217  // Members:
218  /**
219  * @brief Returns true if the external file is open.
220  */
221  bool
222  is_open() const throw()
223  { return _M_file.is_open(); }
224 
225  /**
226  * @brief Opens an external file.
227  * @param s The name of the file.
228  * @param mode The open mode flags.
229  * @return @c this on success, NULL on failure
230  *
231  * If a file is already open, this function immediately fails.
232  * Otherwise it tries to open the file named @a s using the flags
233  * given in @a mode.
234  *
235  * Table 92, adapted here, gives the relation between openmode
236  * combinations and the equivalent fopen() flags.
237  * (NB: lines app, in|out|app, in|app, binary|app, binary|in|out|app,
238  * and binary|in|app per DR 596)
239  * +---------------------------------------------------------+
240  * | ios_base Flag combination stdio equivalent |
241  * |binary in out trunc app |
242  * +---------------------------------------------------------+
243  * | + "w" |
244  * | + + "a" |
245  * | + "a" |
246  * | + + "w" |
247  * | + "r" |
248  * | + + "r+" |
249  * | + + + "w+" |
250  * | + + + "a+" |
251  * | + + "a+" |
252  * +---------------------------------------------------------+
253  * | + + "wb" |
254  * | + + + "ab" |
255  * | + + "ab" |
256  * | + + + "wb" |
257  * | + + "rb" |
258  * | + + + "r+b" |
259  * | + + + + "w+b" |
260  * | + + + + "a+b" |
261  * | + + + "a+b" |
262  * +---------------------------------------------------------+
263  */
264  __filebuf_type*
265  open(const char* __s, ios_base::openmode __mode);
266 
267 #ifdef __GXX_EXPERIMENTAL_CXX0X__
268  /**
269  * @brief Opens an external file.
270  * @param s The name of the file.
271  * @param mode The open mode flags.
272  * @return @c this on success, NULL on failure
273  */
274  __filebuf_type*
275  open(const std::string& __s, ios_base::openmode __mode)
276  { return open(__s.c_str(), __mode); }
277 #endif
278 
279  /**
280  * @brief Closes the currently associated file.
281  * @return @c this on success, NULL on failure
282  *
283  * If no file is currently open, this function immediately fails.
284  *
285  * If a "put buffer area" exists, @c overflow(eof) is called to flush
286  * all the characters. The file is then closed.
287  *
288  * If any operations fail, this function also fails.
289  */
290  __filebuf_type*
291  close();
292 
293  protected:
294  void
295  _M_allocate_internal_buffer();
296 
297  void
298  _M_destroy_internal_buffer() throw();
299 
300  // [27.8.1.4] overridden virtual functions
301  virtual streamsize
302  showmanyc();
303 
304  // Stroustrup, 1998, p. 628
305  // underflow() and uflow() functions are called to get the next
306  // character from the real input source when the buffer is empty.
307  // Buffered input uses underflow()
308 
309  virtual int_type
310  underflow();
311 
312  virtual int_type
313  pbackfail(int_type __c = _Traits::eof());
314 
315  // Stroustrup, 1998, p 648
316  // The overflow() function is called to transfer characters to the
317  // real output destination when the buffer is full. A call to
318  // overflow(c) outputs the contents of the buffer plus the
319  // character c.
320  // 27.5.2.4.5
321  // Consume some sequence of the characters in the pending sequence.
322  virtual int_type
323  overflow(int_type __c = _Traits::eof());
324 
325  // Convert internal byte sequence to external, char-based
326  // sequence via codecvt.
327  bool
328  _M_convert_to_external(char_type*, streamsize);
329 
330  /**
331  * @brief Manipulates the buffer.
332  * @param s Pointer to a buffer area.
333  * @param n Size of @a s.
334  * @return @c this
335  *
336  * If no file has been opened, and both @a s and @a n are zero, then
337  * the stream becomes unbuffered. Otherwise, @c s is used as a
338  * buffer; see
339  * http://gcc.gnu.org/onlinedocs/libstdc++/manual/bk01pt11ch25s02.html
340  * for more.
341  */
342  virtual __streambuf_type*
343  setbuf(char_type* __s, streamsize __n);
344 
345  virtual pos_type
346  seekoff(off_type __off, ios_base::seekdir __way,
347  ios_base::openmode __mode = ios_base::in | ios_base::out);
348 
349  virtual pos_type
350  seekpos(pos_type __pos,
351  ios_base::openmode __mode = ios_base::in | ios_base::out);
352 
353  // Common code for seekoff and seekpos
354  pos_type
355  _M_seek(off_type __off, ios_base::seekdir __way, __state_type __state);
356 
357  virtual int
358  sync();
359 
360  virtual void
361  imbue(const locale& __loc);
362 
363  virtual streamsize
364  xsgetn(char_type* __s, streamsize __n);
365 
366  virtual streamsize
367  xsputn(const char_type* __s, streamsize __n);
368 
369  // Flushes output buffer, then writes unshift sequence.
370  bool
371  _M_terminate_output();
372 
373  /**
374  * This function sets the pointers of the internal buffer, both get
375  * and put areas. Typically:
376  *
377  * __off == egptr() - eback() upon underflow/uflow ('read' mode);
378  * __off == 0 upon overflow ('write' mode);
379  * __off == -1 upon open, setbuf, seekoff/pos ('uncommitted' mode).
380  *
381  * NB: epptr() - pbase() == _M_buf_size - 1, since _M_buf_size
382  * reflects the actual allocated memory and the last cell is reserved
383  * for the overflow char of a full put area.
384  */
385  void
386  _M_set_buffer(streamsize __off)
387  {
388  const bool __testin = _M_mode & ios_base::in;
389  const bool __testout = _M_mode & ios_base::out;
390 
391  if (__testin && __off > 0)
392  this->setg(_M_buf, _M_buf, _M_buf + __off);
393  else
394  this->setg(_M_buf, _M_buf, _M_buf);
395 
396  if (__testout && __off == 0 && _M_buf_size > 1 )
397  this->setp(_M_buf, _M_buf + _M_buf_size - 1);
398  else
399  this->setp(NULL, NULL);
400  }
401  };
402 
403  // [27.8.1.5] Template class basic_ifstream
404  /**
405  * @brief Controlling input for files.
406  * @ingroup io
407  *
408  * This class supports reading from named files, using the inherited
409  * functions from std::basic_istream. To control the associated
410  * sequence, an instance of std::basic_filebuf is used, which this page
411  * refers to as @c sb.
412  */
413  template<typename _CharT, typename _Traits>
414  class basic_ifstream : public basic_istream<_CharT, _Traits>
415  {
416  public:
417  // Types:
418  typedef _CharT char_type;
419  typedef _Traits traits_type;
420  typedef typename traits_type::int_type int_type;
421  typedef typename traits_type::pos_type pos_type;
422  typedef typename traits_type::off_type off_type;
423 
424  // Non-standard types:
425  typedef basic_filebuf<char_type, traits_type> __filebuf_type;
426  typedef basic_istream<char_type, traits_type> __istream_type;
427 
428  private:
429  __filebuf_type _M_filebuf;
430 
431  public:
432  // Constructors/Destructors:
433  /**
434  * @brief Default constructor.
435  *
436  * Initializes @c sb using its default constructor, and passes
437  * @c &sb to the base class initializer. Does not open any files
438  * (you haven't given it a filename to open).
439  */
440  basic_ifstream() : __istream_type(), _M_filebuf()
441  { this->init(&_M_filebuf); }
442 
443  /**
444  * @brief Create an input file stream.
445  * @param s Null terminated string specifying the filename.
446  * @param mode Open file in specified mode (see std::ios_base).
447  *
448  * @c ios_base::in is automatically included in @a mode.
449  *
450  * Tip: When using std::string to hold the filename, you must use
451  * .c_str() before passing it to this constructor.
452  */
453  explicit
454  basic_ifstream(const char* __s, ios_base::openmode __mode = ios_base::in)
455  : __istream_type(), _M_filebuf()
456  {
457  this->init(&_M_filebuf);
458  this->open(__s, __mode);
459  }
460 
461 #ifdef __GXX_EXPERIMENTAL_CXX0X__
462  /**
463  * @brief Create an input file stream.
464  * @param s std::string specifying the filename.
465  * @param mode Open file in specified mode (see std::ios_base).
466  *
467  * @c ios_base::in is automatically included in @a mode.
468  */
469  explicit
470  basic_ifstream(const std::string& __s,
471  ios_base::openmode __mode = ios_base::in)
472  : __istream_type(), _M_filebuf()
473  {
474  this->init(&_M_filebuf);
475  this->open(__s, __mode);
476  }
477 #endif
478 
479  /**
480  * @brief The destructor does nothing.
481  *
482  * The file is closed by the filebuf object, not the formatting
483  * stream.
484  */
485  ~basic_ifstream()
486  { }
487 
488  // Members:
489  /**
490  * @brief Accessing the underlying buffer.
491  * @return The current basic_filebuf buffer.
492  *
493  * This hides both signatures of std::basic_ios::rdbuf().
494  */
495  __filebuf_type*
496  rdbuf() const
497  { return const_cast<__filebuf_type*>(&_M_filebuf); }
498 
499  /**
500  * @brief Wrapper to test for an open file.
501  * @return @c rdbuf()->is_open()
502  */
503  bool
504  is_open()
505  { return _M_filebuf.is_open(); }
506 
507  // _GLIBCXX_RESOLVE_LIB_DEFECTS
508  // 365. Lack of const-qualification in clause 27
509  bool
510  is_open() const
511  { return _M_filebuf.is_open(); }
512 
513  /**
514  * @brief Opens an external file.
515  * @param s The name of the file.
516  * @param mode The open mode flags.
517  *
518  * Calls @c std::basic_filebuf::open(s,mode|in). If that function
519  * fails, @c failbit is set in the stream's error state.
520  *
521  * Tip: When using std::string to hold the filename, you must use
522  * .c_str() before passing it to this constructor.
523  */
524  void
525  open(const char* __s, ios_base::openmode __mode = ios_base::in)
526  {
527  if (!_M_filebuf.open(__s, __mode | ios_base::in))
528  this->setstate(ios_base::failbit);
529  else
530  // _GLIBCXX_RESOLVE_LIB_DEFECTS
531  // 409. Closing an fstream should clear error state
532  this->clear();
533  }
534 
535 #ifdef __GXX_EXPERIMENTAL_CXX0X__
536  /**
537  * @brief Opens an external file.
538  * @param s The name of the file.
539  * @param mode The open mode flags.
540  *
541  * Calls @c std::basic_filebuf::open(s,mode|in). If that function
542  * fails, @c failbit is set in the stream's error state.
543  */
544  void
545  open(const std::string& __s, ios_base::openmode __mode = ios_base::in)
546  {
547  if (!_M_filebuf.open(__s, __mode | ios_base::in))
548  this->setstate(ios_base::failbit);
549  else
550  // _GLIBCXX_RESOLVE_LIB_DEFECTS
551  // 409. Closing an fstream should clear error state
552  this->clear();
553  }
554 #endif
555 
556  /**
557  * @brief Close the file.
558  *
559  * Calls @c std::basic_filebuf::close(). If that function
560  * fails, @c failbit is set in the stream's error state.
561  */
562  void
563  close()
564  {
565  if (!_M_filebuf.close())
566  this->setstate(ios_base::failbit);
567  }
568  };
569 
570 
571  // [27.8.1.8] Template class basic_ofstream
572  /**
573  * @brief Controlling output for files.
574  * @ingroup io
575  *
576  * This class supports reading from named files, using the inherited
577  * functions from std::basic_ostream. To control the associated
578  * sequence, an instance of std::basic_filebuf is used, which this page
579  * refers to as @c sb.
580  */
581  template<typename _CharT, typename _Traits>
582  class basic_ofstream : public basic_ostream<_CharT,_Traits>
583  {
584  public:
585  // Types:
586  typedef _CharT char_type;
587  typedef _Traits traits_type;
588  typedef typename traits_type::int_type int_type;
589  typedef typename traits_type::pos_type pos_type;
590  typedef typename traits_type::off_type off_type;
591 
592  // Non-standard types:
593  typedef basic_filebuf<char_type, traits_type> __filebuf_type;
594  typedef basic_ostream<char_type, traits_type> __ostream_type;
595 
596  private:
597  __filebuf_type _M_filebuf;
598 
599  public:
600  // Constructors:
601  /**
602  * @brief Default constructor.
603  *
604  * Initializes @c sb using its default constructor, and passes
605  * @c &sb to the base class initializer. Does not open any files
606  * (you haven't given it a filename to open).
607  */
608  basic_ofstream(): __ostream_type(), _M_filebuf()
609  { this->init(&_M_filebuf); }
610 
611  /**
612  * @brief Create an output file stream.
613  * @param s Null terminated string specifying the filename.
614  * @param mode Open file in specified mode (see std::ios_base).
615  *
616  * @c ios_base::out|ios_base::trunc is automatically included in
617  * @a mode.
618  *
619  * Tip: When using std::string to hold the filename, you must use
620  * .c_str() before passing it to this constructor.
621  */
622  explicit
623  basic_ofstream(const char* __s,
624  ios_base::openmode __mode = ios_base::out|ios_base::trunc)
625  : __ostream_type(), _M_filebuf()
626  {
627  this->init(&_M_filebuf);
628  this->open(__s, __mode);
629  }
630 
631 #ifdef __GXX_EXPERIMENTAL_CXX0X__
632  /**
633  * @brief Create an output file stream.
634  * @param s std::string specifying the filename.
635  * @param mode Open file in specified mode (see std::ios_base).
636  *
637  * @c ios_base::out|ios_base::trunc is automatically included in
638  * @a mode.
639  */
640  explicit
641  basic_ofstream(const std::string& __s,
642  ios_base::openmode __mode = ios_base::out|ios_base::trunc)
643  : __ostream_type(), _M_filebuf()
644  {
645  this->init(&_M_filebuf);
646  this->open(__s, __mode);
647  }
648 #endif
649 
650  /**
651  * @brief The destructor does nothing.
652  *
653  * The file is closed by the filebuf object, not the formatting
654  * stream.
655  */
656  ~basic_ofstream()
657  { }
658 
659  // Members:
660  /**
661  * @brief Accessing the underlying buffer.
662  * @return The current basic_filebuf buffer.
663  *
664  * This hides both signatures of std::basic_ios::rdbuf().
665  */
666  __filebuf_type*
667  rdbuf() const
668  { return const_cast<__filebuf_type*>(&_M_filebuf); }
669 
670  /**
671  * @brief Wrapper to test for an open file.
672  * @return @c rdbuf()->is_open()
673  */
674  bool
675  is_open()
676  { return _M_filebuf.is_open(); }
677 
678  // _GLIBCXX_RESOLVE_LIB_DEFECTS
679  // 365. Lack of const-qualification in clause 27
680  bool
681  is_open() const
682  { return _M_filebuf.is_open(); }
683 
684  /**
685  * @brief Opens an external file.
686  * @param s The name of the file.
687  * @param mode The open mode flags.
688  *
689  * Calls @c std::basic_filebuf::open(s,mode|out|trunc). If that
690  * function fails, @c failbit is set in the stream's error state.
691  *
692  * Tip: When using std::string to hold the filename, you must use
693  * .c_str() before passing it to this constructor.
694  */
695  void
696  open(const char* __s,
697  ios_base::openmode __mode = ios_base::out | ios_base::trunc)
698  {
699  if (!_M_filebuf.open(__s, __mode | ios_base::out))
700  this->setstate(ios_base::failbit);
701  else
702  // _GLIBCXX_RESOLVE_LIB_DEFECTS
703  // 409. Closing an fstream should clear error state
704  this->clear();
705  }
706 
707 #ifdef __GXX_EXPERIMENTAL_CXX0X__
708  /**
709  * @brief Opens an external file.
710  * @param s The name of the file.
711  * @param mode The open mode flags.
712  *
713  * Calls @c std::basic_filebuf::open(s,mode|out|trunc). If that
714  * function fails, @c failbit is set in the stream's error state.
715  */
716  void
717  open(const std::string& __s,
718  ios_base::openmode __mode = ios_base::out | ios_base::trunc)
719  {
720  if (!_M_filebuf.open(__s, __mode | ios_base::out))
721  this->setstate(ios_base::failbit);
722  else
723  // _GLIBCXX_RESOLVE_LIB_DEFECTS
724  // 409. Closing an fstream should clear error state
725  this->clear();
726  }
727 #endif
728 
729  /**
730  * @brief Close the file.
731  *
732  * Calls @c std::basic_filebuf::close(). If that function
733  * fails, @c failbit is set in the stream's error state.
734  */
735  void
736  close()
737  {
738  if (!_M_filebuf.close())
739  this->setstate(ios_base::failbit);
740  }
741  };
742 
743 
744  // [27.8.1.11] Template class basic_fstream
745  /**
746  * @brief Controlling input and output for files.
747  * @ingroup io
748  *
749  * This class supports reading from and writing to named files, using
750  * the inherited functions from std::basic_iostream. To control the
751  * associated sequence, an instance of std::basic_filebuf is used, which
752  * this page refers to as @c sb.
753  */
754  template<typename _CharT, typename _Traits>
755  class basic_fstream : public basic_iostream<_CharT, _Traits>
756  {
757  public:
758  // Types:
759  typedef _CharT char_type;
760  typedef _Traits traits_type;
761  typedef typename traits_type::int_type int_type;
762  typedef typename traits_type::pos_type pos_type;
763  typedef typename traits_type::off_type off_type;
764 
765  // Non-standard types:
766  typedef basic_filebuf<char_type, traits_type> __filebuf_type;
767  typedef basic_ios<char_type, traits_type> __ios_type;
768  typedef basic_iostream<char_type, traits_type> __iostream_type;
769 
770  private:
771  __filebuf_type _M_filebuf;
772 
773  public:
774  // Constructors/destructor:
775  /**
776  * @brief Default constructor.
777  *
778  * Initializes @c sb using its default constructor, and passes
779  * @c &sb to the base class initializer. Does not open any files
780  * (you haven't given it a filename to open).
781  */
782  basic_fstream()
783  : __iostream_type(), _M_filebuf()
784  { this->init(&_M_filebuf); }
785 
786  /**
787  * @brief Create an input/output file stream.
788  * @param s Null terminated string specifying the filename.
789  * @param mode Open file in specified mode (see std::ios_base).
790  *
791  * Tip: When using std::string to hold the filename, you must use
792  * .c_str() before passing it to this constructor.
793  */
794  explicit
795  basic_fstream(const char* __s,
796  ios_base::openmode __mode = ios_base::in | ios_base::out)
797  : __iostream_type(NULL), _M_filebuf()
798  {
799  this->init(&_M_filebuf);
800  this->open(__s, __mode);
801  }
802 
803 #ifdef __GXX_EXPERIMENTAL_CXX0X__
804  /**
805  * @brief Create an input/output file stream.
806  * @param s Null terminated string specifying the filename.
807  * @param mode Open file in specified mode (see std::ios_base).
808  */
809  explicit
810  basic_fstream(const std::string& __s,
811  ios_base::openmode __mode = ios_base::in | ios_base::out)
812  : __iostream_type(NULL), _M_filebuf()
813  {
814  this->init(&_M_filebuf);
815  this->open(__s, __mode);
816  }
817 #endif
818 
819  /**
820  * @brief The destructor does nothing.
821  *
822  * The file is closed by the filebuf object, not the formatting
823  * stream.
824  */
825  ~basic_fstream()
826  { }
827 
828  // Members:
829  /**
830  * @brief Accessing the underlying buffer.
831  * @return The current basic_filebuf buffer.
832  *
833  * This hides both signatures of std::basic_ios::rdbuf().
834  */
835  __filebuf_type*
836  rdbuf() const
837  { return const_cast<__filebuf_type*>(&_M_filebuf); }
838 
839  /**
840  * @brief Wrapper to test for an open file.
841  * @return @c rdbuf()->is_open()
842  */
843  bool
844  is_open()
845  { return _M_filebuf.is_open(); }
846 
847  // _GLIBCXX_RESOLVE_LIB_DEFECTS
848  // 365. Lack of const-qualification in clause 27
849  bool
850  is_open() const
851  { return _M_filebuf.is_open(); }
852 
853  /**
854  * @brief Opens an external file.
855  * @param s The name of the file.
856  * @param mode The open mode flags.
857  *
858  * Calls @c std::basic_filebuf::open(s,mode). If that
859  * function fails, @c failbit is set in the stream's error state.
860  *
861  * Tip: When using std::string to hold the filename, you must use
862  * .c_str() before passing it to this constructor.
863  */
864  void
865  open(const char* __s,
866  ios_base::openmode __mode = ios_base::in | ios_base::out)
867  {
868  if (!_M_filebuf.open(__s, __mode))
869  this->setstate(ios_base::failbit);
870  else
871  // _GLIBCXX_RESOLVE_LIB_DEFECTS
872  // 409. Closing an fstream should clear error state
873  this->clear();
874  }
875 
876 #ifdef __GXX_EXPERIMENTAL_CXX0X__
877  /**
878  * @brief Opens an external file.
879  * @param s The name of the file.
880  * @param mode The open mode flags.
881  *
882  * Calls @c std::basic_filebuf::open(s,mode). If that
883  * function fails, @c failbit is set in the stream's error state.
884  */
885  void
886  open(const std::string& __s,
887  ios_base::openmode __mode = ios_base::in | ios_base::out)
888  {
889  if (!_M_filebuf.open(__s, __mode))
890  this->setstate(ios_base::failbit);
891  else
892  // _GLIBCXX_RESOLVE_LIB_DEFECTS
893  // 409. Closing an fstream should clear error state
894  this->clear();
895  }
896 #endif
897 
898  /**
899  * @brief Close the file.
900  *
901  * Calls @c std::basic_filebuf::close(). If that function
902  * fails, @c failbit is set in the stream's error state.
903  */
904  void
905  close()
906  {
907  if (!_M_filebuf.close())
908  this->setstate(ios_base::failbit);
909  }
910  };
911 
912 _GLIBCXX_END_NAMESPACE
913 
914 #ifndef _GLIBCXX_EXPORT_TEMPLATE
915 # include <bits/fstream.tcc>
916 #endif
917 
918 #endif /* _GLIBCXX_FSTREAM */